Energy conservation is a proven means to reduce the operating costs of hotels. But many lodging facility operators shun attempts at saving energy in the guest-rooms, as they are concerned about the negative impact that such measures may have on guest perception and comfort.
A modern guestroom uses approximately 25 Kilowatt-hours (KWHr) of electricity (or equivalent fuel) each day. Based on a cost estimate of $0.07 per KWHr, this amounts to about $1.75 per day per room. This figure assumes the following appliances are used in a typical room: Heating/Ventilation/Air-Conditioning (HVAC), lamps (portable), lights (fixed), television, radio, and minibar. A mini-bar is a convenient store of goods within each room, usually within a refrigerator, that can be accessed by the guest at his or her discretion.
With the exception of the minibar, the electrical power consumption by the appliances is manually controlled, and the amount of electricity used by these appliances can be reduced using an energy management system (EMS). In the case of the HVAC system, a well-designed EMS can reduce not only the number of hours the HVAC system is used each day, but can also reduce the average power required. The EMS can set back the HVAC temperature whenever a room is not rented and, when rented, whenever a guest is not in the room. The EMS will turn off lamps and lights when the guest or housekeeping leaves the room. The EMS can turn off the television when the room is not rented, and it can open or close the drapes to control heat exchange with the outside.
In modern lodging facilities, the EMS is part of a larger guest room control system, which also includes a direct digital control (DDC) system and a central electrical lock system (CELS). The DDC system allows a guest to remotely control the lamps, lights, shades, television, and other appliances from a single control station. The CELS connects guestroom doors to a central computer in the hotel for logging keycard access operations and for enabling and disabling access cards.
Guest room control systems typically comprise a control computer or device for each room. The control computer receives data from various sensors throughout the room and, in response to the feedback provided by the sensors, operates a number of remote room control devices. Such remote sensors include, for example, motion sensors, temperature sensors, smoke detectors, and door and other closure switches. Such remote room control devices include, for example, thermostats and associated relays for heating, ventilation and air conditioning (HVAC) equipment, electronic locks, lighting control switches and relays, and motors and switches for opening and closing drapes. The central control computer uses the data and control devices to, for example, adjust the room's temperature, determine and annunciate whether the room is occupied or unoccupied, determine and annunciate whether the room's mini-bar has been accessed, sound fire and emergency alarms, turn lights on or off, permit or deny access to the room, open and close drapes, turn audio-visual equipment on or off, and perform other functions related to controlling equipment or annunciating status in rooms. The central control computer located in each room can be linked to a single master central control computer. The central control computer from each room provides data to the master central control computer from which such data is disseminated to display and control terminals at housekeeping, front desk, security, engineering or any number of other locations in order to provide hotel personnel with access to the data and with the ability to remotely control various room functions or settings from such terminals.
Such guest room control systems work well to provide conveniences to the guest. However, these systems typically require a specific sensor for a specific purpose, thus, many different sensors may be required for a single guest room. For example, a main switch is used to determine whether a guest opened the main door. Another switch is used to determine whether the guest opened the mini-bar door. Yet another switch is used to determine whether the guest opened a door to a patio, such as a lanai or sliding door. Therefore, a number of different sensors (and corresponding receivers) may be incorporated in a guest room. While multiple sensors provide greater control of the power consumption for a guest room, the system installation, operation and maintenance becomes more complex and costly.